Mercedes-Benz SL 63 AMG
6.2-litre naturally aspirated V8, hand-built in Affalterbach to the 'One Man, One Engine' principle. 457–525 hp without any forced induction, rev limit at 7,200 rpm. The sound defines an era: a deep, bass-heavy rumble at 3,000 rpm, a scream above 5,000 that recalls American V8 racing engines. Throttle response is immediate — no turbo lag, no hesitation, every throttle command is executed instantly. Critical issue number one: camshafts wear out through inadequate cold-start lubrication with the factory 0W-40 oil. Switch to Ravenol 5W-40 RCS, let the engine idle for 10 seconds after a cold start, stay below 3,000 rpm until fully warm. Head bolt corrosion on engine numbers below 060658 (up to approx. 2010) — check without fail. Star Technical Bulletin 05.20/20b documents the tappet problem officially. Parts availability is becoming increasingly difficult — hydraulic tappets A1560500225 sometimes not available for months. Maintain the M156 properly and you have one of the most emotional V8s of the last 30 years.
Open V8 Roadster — the Best SL Sound of All Time
SL 63 AMG R230: V8 naturally aspirated engine with Vario roof — roof closed a GT coupé, roof open a V8 roadster. The M156 sounds fantastic in the open SL — deeper, more direct than in a closed car. Heavier than the C63, but on long distances the better sports tourer. Last SL generation with a true naturally aspirated engine.
Engine Weaknesses 10
All M156 up to engine number 060658 affected: head bolts corrode through coolant contact at the bolt head, in worst case break off. Coolant enters the combustion chamber — engine damage. Mercedes fitted improved bolts from approx. 2010 (20x A1560160769 + 4x N000000005754, approx. 108 EUR net). Preventive replacement strongly recommended.
Symptoms: Coolant loss without visible leak, white smoke from exhaust, oil-coolant mixture, check engine light, misfires on individual cylinders.
Main problem of the M156: the factory 0W-40 oil drains from the camshafts at standstill; at cold start the lobes run briefly dry. Wear deteriorates exponentially. Camshaft regrinding (TechnoCam and others) as a cheaper alternative to new parts — 50% saving. Always replace the 32 hydraulic tappets (INA A1560500225) at the same time.
Symptoms: Metallic ticking on cold start that disappears after 30–60 seconds, rough idle, power loss in the upper rev range. Remove valve cover and check lobe tips for wear.
The fit of the locking plate in the camshaft adjuster widens over time — the adjuster slips, timing shifts. Clattering on cold start is the first symptom. Reinforced locking plates (300–1,000 EUR for 4 pieces) as a permanent solution. Bearing cap torque 10 Nm, adjuster 45 Nm + 90°.
Symptoms: Rattling/clattering on cold start for 2–10 seconds, disappears after oil pressure build-up. With advanced wear: also audible when warm, rough idle, shifted timing, power loss.
The plastic timing chain guide rails become brittle over time and can break. Mercedes has developed reinforced replacements. A broken guide rail fragment in the timing drive can cause chain skip and valve damage. Preventive replacement at >100,000 km recommended.
Symptoms: Rattling from the front of the engine that gets louder with rpm, chain tensioner at its stop, check engine light with timing fault codes.
The 32 hydraulic tappets (INA-made, A1560500225) wear alongside the camshafts. Star Bulletin 05.20/20b documents the issue officially. SLS Black Series tappets with improved coating (~35 EUR each vs. 8 EUR each standard) as an upgrade. Parts availability in 2024 was partially unavailable for months.
Symptoms: Metallic ticking/clattering especially on cold start and at idle. Initially only on individual cylinders, then increasingly all. If seized in the head: sudden knocking, valve damage possible.
The factory 0W-40 oil drains completely from the camshafts during standstill. At cold start there is a brief dry-running condition. Switching to Ravenol 5W-40 RCS noticeably resolves this. After cold start, allow 10 seconds idle before revving above 3,000 rpm after reaching operating temperature. Oil consumption of 0.5–1 L/1,000 km with spirited use is normal.
Symptoms: Bluish exhaust smoke after extended standstill on first start, oil level warning with spirited driving, elevated oil consumption especially in summer.
From 80,000–100,000 km the valve stem seals harden and allow oil into the combustion chamber. Typical of high-rpm V8 engines. Repair requires removing the camshafts — worthwhile combined with a camshaft service.
Symptoms: Bluish smoke on throttle application after overrun (traffic light start after downhill), oil consumption rises to >1 L/1,000 km, oil deposits on spark plugs.
The 8 individual ignition coils are wear items and fail sporadically from 60,000 km. If ignored, catalytic converter damage from unburnt fuel is a risk. Always replace all 8 at the same time — cheap wear part, high consequential damage if ignored.
Symptoms: Check engine light, misfires on individual cylinders (felt as hesitation under load), P0300–P0308 fault codes, slight power loss.
The magnesium intake manifold corrodes internally over time — especially on vehicles that sit for long periods. Deposits reduce airflow. Reconditioning the manifold is recommended during a camshaft service. New parts are increasingly difficult to source.
Symptoms: Slight power loss in the upper rev range, visible white corrosion marks on intake manifold removal, rougher throttle response.
The AMG-specific composite brake discs (steel-aluminium compound) last 30,000–50,000 km with spirited use. Replacement considerably more expensive than conventional discs. When buying used: brake condition is a decisive price negotiation point.
Symptoms: Brake disc wear indicator, vibration when braking from high speed, visible grooves and cracks on disc, squealing with cold brakes.
Vehicle Weaknesses 11
The ABC hydraulic pump can develop cracks and lose pressure from 120 bar down to 60 bar. Suspension can no longer maintain ride height, soft and vague handling characteristics.
The hydraulic fluid absorbs moisture, rubber components decompose and contaminate the system. Valve block and lines develop leaks. Annual oil change prevents major damage.
The SBC unit is designed for approximately 400,000 brake cycles and fails at this point. When it fails, braking effectiveness is severely reduced — a safety risk. Mercedes extended the warranty to 25 years.
The electric motor of the roof pump burns out. Windings and circuit board affected. Pump runs audibly for longer or not at all. Specialist repair from 595 EUR, Mercedes dealer significantly more expensive.
Defective control unit causes functional failures of the vario roof. Roof stops in various positions, headrests raise but do not return.
The electric folding roof develops problems with limit switches and hydraulic components. When the sequence is disrupted, the roof no longer opens or closes.
The R230 develops clicking and creaking noises in the steering rack, often at every third steering input or under load. Track rod ends are a frequent cause. The steering rack can also lose hydraulic oil.
Typical rust spots develop at the tips of the rear quarter panels at the transition to the door and sill. Moisture and dirt collect there. Rust can grow from the inside out and is often only visible at a late stage.
The Vario roof contains 11 hydraulic cylinders. The seals become porous with age; escaping oil damages trim panels and the boot. Seal sets for all cylinders are available for around 99 EUR.
Despite the hardtop, water enters the boot. Porous seals at the interlocking points of the Vario roof as well as blocked drainage channels at the rear screen.
The plastic hinges on the side parcel shelf flaps become brittle after approximately 15 years and snap off. OEM replacement around 1,600 EUR for both sides, a brass repair kit is available for around 90 EUR.
Reports & Tests
275 owner complaints filed with NHTSA (2001–2012). Most reported: Suspension (77), Brakes (73), Electrical (41).